You and a Colleague Are Working on a Rare Peruvian

You and a colleague are working on a rare Peruvian llama that appears to be susceptible to diabetes, a disease related to insulin function. Your colleague has established a somatic-cell hybrid panel, and you would like to figure out to which llama chromosome the gene that encodes the llama insulin receptor maps. You also have an assay that allows you to detect which of the somatic-cell lines can produce the insulin receptor. You assay the colleague's somatic-cell hybrid panel and get the following results. Which of the 74 llama chromosomes is the gene on? $$\begin{array} { l l l } \text { Line \# } & \text { Llama chromosomes } & \text { Assay } \\\hline 1 & 7,10,15,29,41,55,68 & - \\2 & 4,8,16,31,44,56,70 & - \\3 & 9,12,18,52,54,61,73 & + \\4 & 1,8,13,22,33,45,59 & - \\5 & 2,11,14,18,23,49,62 & + \\6 & 5,12,15,24,35,47,63 & - \\7 & 3,17,21,32,43,58,72 & - \\8 & 7,21,25,36,53,64 & - \\9 & 1,3,9,28,37,48,65 & - \\10 & 13,22,27,38,50,66,19 & - \\11 & 4,6,12,18,20,40,67 & + \\12 & 2,16,26,34,51,69 & - \\13 & 10,14,17,39,46,57,74 & - \\14 & 5,11,19,30,42,60,71 & -\end{array}$$

A) 55
B) 7
C) 41
D) 68
E) 18